Abstract

The phenomenon of singing wineglasses has been a fascination since the Renaissance times and many papers has been made on the subject. A work by A. P. French shows the relationship between the frequency produced and liquid height by wineglasses is given by: , where the quantity α as a sum of factors in the order of unity. This paper verifies the dependence of α with respect to the geometry of the wine glass. Furthermore, it also investigate the effect of the different liquids to the value of α. Slip-stick effect and impact method were used to activate the wine glass filled with liquid in order to produce a sound. The sound is captured through the microphone which is then analyzed using Fast Fourier Transform in order to determine its frequency components for different liquid height. The value of α is determined from the relationship between the frequency and liquid height. The experiment utilizes four (4) wine glasses and one (1) cocktail glass of different shapes and sizes. Effects of three (3) different liquids were also considered. It was observed that for any wineglass and any liquid, the frequency of the vibrations when struck decreased when the liquid level increased, although the relationship was non-linear. For the typical wineglass, the obtained frequencies for water using the slip-stick effect were similar to that of which was obtained by striking. From the graph of , the value of α was determined from the slope and found out that it is dependent on the ratio of densities of the liquid and type of glass. Experimental results show that the value of α is not related to the type of liquid used but affected by the geometry of the wine glass.

Index Terms

natural frequency, singing wineglass, vibration

Abstract

This work aims to show a simple method to study complex motion using the camera on a cell phone. The experiment can be easily replicated in most undergraduate laboratories. The experiment utilizes the freeware Tracker Video Analysis and Modeling tool to study the motion of a damped physical pendulum. The physical pendulum used is a thin rectangular plate that is assumed to have a homogenous distribution of its materials and thus have uniform density. The pendulum is displaced by ~5° with respect to its equilibrium position. The resulting behavior is recorded using a cellular phone camera and analyzed using the Tracker software. We used different pivot points for each trial. The freeware Tracker software accurately pinpoints each position of the tip of the physical pendulum in space with respect to time. The data which describes the overall motion of the pendulum is used to get the pendulum’s equation of motion. The obtained equation of motion does not fit the real data perfectly, but can accurately model the oscillation of the pendulum. The theoretical angular frequency (3.82 rad/s) and experimental angular frequency (3.89 rad/s) of the oscillation is comparable having a percent difference of 1.83% only.

Index Terms

Dynamic motion modeling, Harmonic motion, Damped motion, Physical Pendulum, Tracker software

Abstract

Cancer, the third leading cause of morbidity and mortality, remains a national health priority in the country with significant implications for individuals, families, communities, and the health system. 189 of every 100,000 Filipinos are afflicted with cancer while four Filipinos die of cancer every hour. Metastasis accounts for the majority of cancer deaths. This happens when a cancer spreads from the place where it first started to another place in the body. The effective detection of circulating tumor cells (CTCs) in the peripheral blood of cancer patients holds promise as an alternative because of its minimally invasive and easy sampling procedures (i.e., blood drawing). Microfluidics is capable of performing separations with high sensitivity thus becoming a highly useful tool for this application. In this study, a multi-orifice microchannel design was used. The design was tested to separate osteosarcoma cells (SaOs-2) from red blood cells (RBCs). It was found that this microfluidic chamber is able to separate cancer cells with an accuracy of up to 42%.

Index Terms

cancer, microfluidics, osteosarcoma, passive

microfluidics, separation

Abstract

Food spoilage is a major problem in the food industry, causing plenty of food produced for human consumption to be wasted each year. This research hopes to aid the agricultural and food industry by prolonging the shelf life of produce, specifically by using plasma activated water (PAW) to wash strawberries and improve their shelf life. Distilled water was exposed to atmospheric pressure plasma jet (APPJ) at varying times. The plasma was produced using niobium electrodes connected to a 15-kV neon sign generator with Ar and O2 as the carrier gases. The strawberries were then submerged in the PAW for 10 minutes with another group submerged in distilled water for control. The strawberries were then evaluated for spoilage using the yeast/mold counts, visual and texture examination, and %water loss. The plasma produced was characterized using optical emission spectroscopy, revealing the presence of Argon, Oxygen, and Reactive Oxygen species in the plasma jet. The presence of these species activated the water exposed to the plasma leading to increased electrolytic conductivity, acidity and oxidation reduction potential as well as showing presence of hydrogen peroxide in the water. These factors contribute to the disinfecting capabilities of PAW. The strawberry group submerged in distilled water was determined to be spoiled 1 day after treatment. The strawberry groups submerged in PAW, on the other hand were all spoiled 3 days after treatment. PAW has shown that it is effective in delaying the spoilage of strawberries.

Index Terms

Atmospheric pressure plasma jet, plasma activated water, spoilage, strawberries

Abstract

Bacterial adhesion is the most common contamination in food and pharmaceutical processing industry. This research aims to impart antibacterial properties to stainless steel material impregnated with silver nanoparticles. Nano-sized silver particles were synthesized via atmospheric pressure plasma jet (APPJ) system onto stainless steel. Optical emission spectroscopy (OES) was used to characterize the species present in the generated plasma. Argon, oxygen, and silver I and II species were detected with the calculated electron temperature of 0.72eV (8,345.52K) which was classified as cold plasma. SEM images showed that silver nanoparticles were non-agglomerated when synthesized at 1mm nozzle-to-substrate distance for 30sec to 180sec treatment time. X-ray fluorescence (XRF) spectrometer confirmed the deposits as silver. Treated and untreated stainless steel samples were tested for antibacterial activity using the standard protocol AATCC 100-2004. The highest antibacterial property of the treated samples was obtained using 30 seconds plasma treatment time with an average percent reductions of 88.22% and 79.71% against Escherichia coli and Staphylococcus aureus respectively. These results demonstrated that silver nanoparticles synthesized on stainless steel via atmospheric pressure plasma jet exhibit antibacterial properties.

Index Terms

antibacterial properties, Atmospheric Pressure Plasma Jet, Silver nanoparticles, stainless steel

Abstract

Noise Pollution has been a prevailing issue in our classrooms that affects the physiological processes and psychological health of our students in public schools specifically. The study aimed to measure the absorption coefficient of waste polyethylene foam, used as dumping material for our laboratory equipment, to determine if we can possibly reuse it as an acoustic material to make our classrooms more conducive to learning. Its absorption coefficient was measured using two-microphone transfer function method. A sample of the foam was inserted into the impedance tube and was exposed in a stimulus to quantify the complex transfer function. The results were used in the calculations for the reflection and absorption coefficient of the material. Uniform and Gaussian white noise were used as excitation signals to test its acoustic properties. Furthermore, the study also investigated the effect of the thickness, (1.0 in. to 2.0 in.), to its efficiency in absorbing sound energy. The results showed that thickness affects the efficiency of the material in absorbing sound energy and the 1-inched thick sample is the most absorbent amongst the thicknesses. Thus, the installation of this type of polymeric foam in our classrooms could possibly help in eradicating the noise pollution experienced by the students and teachers inside the classroom.

Index Terms

Absorption Coefficient, Impedance tube, Transfer function Method, Reflection Coefficient

Abstract

Bs Cas is an Eclipsing binary of W UMA type. Based on the related researches and available data, W UMa stars can be recognized easily by their light curves with near equal minima and continuous light variation. This eclipsing binary star is in constellation Cassiopeia. Bs Cas has a magnitude range of 10.50 – 12.16 V, it has an epoch of 30 Jun 1935 (HJD 2427984.489) and period of 0.44046971 d (10.571273 h). The raw data (CCD images) used in photometry analysis were taken using the database of SOAO using 61 cm Telescope / FLI 4k CCD from September 20, 2014 evening to September 21, 2014 (2:5 5:17) dawn by Jang Ho Park. The researchers utilized the IRAF (Image Reduction and Analysis Facility) program in order to produce a clear and accurate image. Post processing involves extracting the magnitude of Bs Cas and standard stars then analyzing light curves. The result of the research shows that the delta magnitude was at a maximum at the times 2456890.31757 HJD (Bs Cas – S1), 2456890.23478 HJD (Bs Cas – S2) and 2456890.24017 HJD (Bs Cas – S3). It was a minimum at 2456890.3445 HJD. The researchers assume that the observation and the data available may vary due to some physical conditions and technical issues with respect to the program IRAF, however, available data from other sources and plotted light curve validated the efficiency of this program in generating light curves.

Index Terms

Eclipsing binary star, W UMA type, photometry analysis, pre-and post-processing Data Reduction, continues light variation, IRAF

Abstract

The determination of the flow rate in terms of velocity, head pressure change and volumetric flow rate from the water tank reservoir of Martires de Barbastro Building of Claret School of Zamboanga City using theoretical calculations following Bernoulli’s Principle and Equation of Continuity and other related physical and mathematical definitions in fluid mechanics.

Index Terms

Bernoulli’s principle. continuity, flow rate, Claret School